Co-star Michael Trevino will also be “exploring new opportunities” next season, according to executive producer Julie Plec.
After six years of playing Elena Gilbert (and her many doppelgängers), Nina Dobrev has announced that she’s leaving The Vampire Diaries at the end of its current sixth season. She wrote:

Dearest TVD Family,
I’ve just spent the most beautiful weekend on Lake Lanier in Georgia with my own TVD Family, the cast and crew of The Vampire Diaries. I want to be the first to tell you that it wasn’t just a holiday celebration, it was a goodbye party. I always knew I wanted Elena’s story to be a six season adventure, and within those six years I got the journey of a lifetime. I was a human, a vampire, a doppelganger, a crazy immortal, a doppelganger pretending to be human, a human pretending to be a doppelganger. I got kidnapped, killed, resurrected, tortured, cursed, body-snatched, was dead and undead, and there’s still so much more to come before the season finale in May. Elena fell in love not once, but twice, with two epic soulmates, and I myself made some of the best friends I’ll ever know and built an extended family I will love forever.
There’s more to come before we wrap this up, and I promise you’ll get to hear all about my experiences over the next month as we approach the season finale (I have given an exclusive interview for the June issue of SELF Magazine that I am excited for you to see!), but until then I invite you to hop on the roller coaster ride that is Elena Gilbert’s life and join me as I celebrate her and prepare to say goodbye to her — and to my work family — as I move on to the next chapter of my life. I want to share this goodbye with all of you (this weekend’s pictures were just the beginning). You, the wonderful fandom who gave more love, support and passion than anyone could have ever imagined seven years ago, when a young Degrassi girl from Canada showed up in LA to audition for ‘that Twilight TV show.’ ;-) I love you all. Fasten your seatbelts. If you think you know what’s coming, you don’t.
Love, Nina

Julie Plec, executive producer of The Vampire Diaries, said in a statement, “Saying goodbye to Nina is both bittersweet and beautiful. After six-plus years together, the entire cast and crew of The Vampire Diaries has reached a level of closeness that I don’t think any of us ever expected. Nina is excited to spread her wings, get some rest, travel the world and also take it by storm, and we support her a thousand-fold. We will miss Nina and the four hundred characters she played, but we look forward to the insane and exciting challenge of continuing to tell stories of our Salvatore Brothers and our much-loved and gifted ensemble.”
Plec also revealed that Michael Trevino, who has played Tyler Lockwood since Season 1, will not be returning to the show on a regular basis. “Michael has been a beloved member of The Vampire Diaries family since day one,” she said in the statement. “Even though he’s also going to be out in the world exploring new opportunities, we look forward to finding creative ways to make sure he and his character Tyler Lockwood always remain a part of the show.”
Rumors Dobrev was leaving the show began to surface this weekend when several members of the cast and crew posted pictures from a lakeside retreat on Instagram with the hashtag #NinaWeWillMissYou.
It remains to be seen if her exit involves Elena being killed off the show, but Dobrev said that she believes characters need to die for The Vampire Diaries to remain relevant. “In the beginning, the shock value of killing Vicki [Kayla Ewell] in the first few episodes made us stand out,” Dobrev said. “As soon as you start bringing people back, you kinda lose that. I mean, it’s great for me, personally, because I get to hang out with my friends, but from a story standpoint, now you don’t care or believe when someone dies because you’ve seen how easily they can come back. The witches can always fix it, somehow. It’s been six years, so I think it would be good to go down the list and cross them off.”